window.onload = function () {
    var understand = document.querySelector('.understand');
    understand.onclick = function () {
        understand.href = 'index3.html';
    }
    var communicate = document.querySelector('.communicate');
    document.querySelector('.communicate').addEventListener('click', function () {
        communicate.href = 'index4.html';
    })
    var secret = document.querySelector('.secret');
    secret.onclick = function () {
        var password = prompt('暗号');
        if (password === '997422') {
            window.location.href = '../secret/heart.html';
        }

    }
}